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Unique siderite occurrence in Baltic Sea: a clue to siderite-water oxygen isotope fractionation at low temperatures

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Hałas S. , Chlebowski R.

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tom Vol. 48, No 4

317--322

EN

electron microprobe (determination of major cation content) and mass spectrometry (delta13 C and delta18 O analysis). The siderite was interpreted as having formed from metallic iron partly protected from free oxygen access by wood tar with delta13 C = -24 0/00 and from biogenic CO2 produced from this organic matter. Inasmuch as the siderite has highly positive delta3 C values ranging from 8.05 to 15.41 0/00, we deduced that extremely isotopically heavy CO2 was generated in the process of biogenic decomposition of the organic matter. It was found that the delta18 O values of siderite (26.58 to 27.74‰ vs. VSMOW) fit very well to the recalculated curve of Becker (1971) [formula] and to published extrapolated experimental data.

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Graficzna prezentacja składu minerałów ciężkich lessów na wybranych przykładach z obszaru Polski i Ukrainy

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Chlebowski R. , Gozik P. F. , Lindner L.

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tom Vol. 50, nr 6

526-531

PL

Badania składu minerałów ciężkich lessów mają bardzo ważne znaczenie w interpretacjach genetycznych, określaniu warunków akumulacji tych utworów, określaniu obszarów źródłowych i pochodzenia materiału lessotwórczego. Autorzy zalecają badanie nie tylko frakcji minerałów ciężkich, ale i frakcję lekką lessów, gdyż w obydwu tych frakcjach mogą występować minerały o genetycznie zróżnicowanej gęstości, jak np. glaukonit i muskowit. Ze względu na zróżnicowanie cech fizycznych i morfologicznych minerałów ciężkich wydzielono 5 grup mineralnych spośród wszystkich przezroczystych minerałów ciężkich występujących w lessach oraz grupę minerałów nieprzezroczystych. Grupa I - minerały najbardziej odporne na wietrzenie; II - minerały odporne na wietrzenie; III - minerały mało odporne na wietrzenie; IV - minerały najmniej odporne na wietrzenie; V - minerały najbardziej podatne na czynniki eoliczne, o pokroju blaszkowym; VI - minerały nieprzezroczyste. Dla grup I - V sporządzono techniką komputerową radarowe wykresy 5-cio wektorowe, obrazujące tendencje genetyczne badanych lessów, np. wektory I i II nawiązują do zwietrzelin skał magmowych i metamorficznych, wektory III i IV obrazują tendencje "lokalności" pochodzenia materiału lessotwórczego, a wektor V tendencje "eoliczne", obrazując zawartość minerałów o pokroju blaszkowym, podatnych na wywiewanie i transport eoliczny.

EN

Analyses of heavy minerals in loesses are crucial for genetic interpretations, determination of the accumulation conditions, determination of the source areas and the origin of loess material. The authors propose not only to examine the heavy minerals fraction but also the light fraction of loesses, as both fractions can contain minerals with genetically variable density, such as e.g. glauconite and muscovite. Due to variable physical and morphological properties of heavy minerals, five mineral groups as well as a group of non-transparent minerals were distinguished within all transparent heavy minerals occurring in loesses: group I- minerals most resistant to erosion; II-minerals resistant to erosion; HI-minerals poorly resistant to erosion; IV-minerals least resistant to erosion; V-minerals most susceptible to eolian factors, with a platy habit; VI- non-transparent minerals. For groups I-Vradar five-vector graphs were computer generated. The graphs reflect the genetic tendencies of the analysed loesses, e.g., vectors I and II reflect debris ofmagmatic and metamorphic rocks, vectors III and IV reflect the "local" character of the loess material, and vector V reflects "eolian " tendencies, indicating the presence of minerals with a platy habit, susceptible to blowing out and eolian transport.

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Znaczenie występowania glin lodowcowych Polski i Ukrainy

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Lindner L. , Boguckij A. , Chlebowski R. , Gożik P.

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tom Vol. 52, nr 4

331-335

EN

The presence of glacial tills in eight loess type sections documenting, in most cases, a complete rhythm of climatic changes during the last 780 ka (Brunhes epoch) in Poland and Ukraine, allows to precisely establish the age of these tills. The oldest till in Odonów, Kolonia Zadębce, and Bojanice represents the Sanian 2 (Elsterian 2, Okanian) Glaciation. The younger till (in Wąchock, Gradiżsk, and Wjazowok) corresponds to the ice-sheet extent during the Krznanian (Saalian 2, Dnieper 1) Glaciation, and the youn gest till (in Wąchock, Bugaiwka, and Stajki) to the ice-sheet extent during the Odranian (Saalian 3, Dnieper 2) Glaciation. The occurrence of these glacial tills in the discussed loess sections is crucial for the correlation of glacial and extraglacial stratigraphic schemes for the Pleistocene of Europe.

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Stratigraphy and sedimentology of the Bug loess (Pleistocene: Upper Vistulian) between Kiev and Odessa (Ukraine)

71%

Chlebowski R. , Gozhik P. , Lindner L. , Łanczont M. , Wojtanowicz J.

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tom Vol. 47, No 3

261-268

EN

Documented type sections (Vyazivok, Stayky, Uman, Troitskoye, Altestovo, Roxolany and Lebedivka) provide a basis for Pleistocene stratigraphy between Kiev and Odessa, and have been used to characterise the heavy mineral composition and part of the light fraction of the Bug loess in this area. These sections document an almost complete succession of climatic change during the last 780 ka, worked out mostly using loesses and palaeosols though also in the case of the first two sections, of glacial deposits. The heavy mineral composition of the Bug loess in these sections documents five mineral groups on the basis of their resistance to weathering and susceptibility to deflation and aeolian transport. Radar charts with particular mineral groups indicate mineralogical and genetic trends in the loesses. Moreover, in some sections the light fraction of the loess investigated contains derived microfossils (mainly foraminifers) of Cretaceous age, indicating source areas for the loess-forming material, and constraining the palaeowind directions. The data obtained allow distinction of three accumulation zones of the Bug loess in this area, reflecting loesses derived from different source areas and transported by winds from different directions. In northern sections (zone A), the Bug loess was accumulated by winds blowing from the west and north-west. More to the south (zone C), the same loess was accumulated by winds from the east and south-east. Loess preserved in zone B, between these areas, could be accumulated by winds from either of these directions.